Technical Report 596/2

VARIABILITY OF PRACTICE AND THE

TRANSFER OF TRAINING OF MOTOR SKILLS

Craig A. Wrlsberg and Timothy P. Winter

University of Tennessee. Knoxville

BASIC RESEARCH

>- UL 919840

U. S. Army

Research Institute for the Behavioral and Social Sciences

November 1983

Approved for oublit re~eas: distribution unlimite..

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FOR THE BEHAVIORAL AND SOCIAL SCIENCES

A Field Operating Agency under the Jurisdiction of the

Deputy Chief of Staff for Personnel

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EDGAR M. JOHNSON Colonel, IN

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University of Tennessee, Knoxville

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VARIABILITY OF PRACTICE AND THE TRANSFER OF

TRAINING OF MOTOR SKILLS 6. PERFORMING ORG. REPORT NUMBER

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Craig A. Wrisberg and Timothy P. Winter MDA903-81-C-0216

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19. KEY WORDS (Cotfnue on relerse ide ft neceesar and Identify by block nmiber)

Variability of practice Timing Skill acquisition Transfer of training Stimulus velocity Practice effects

Open skill Movement distance

Closed skill Movement time

Anticipation Schema 20. ABSTRACT (Continue on reveree ede ft necessary ad Idet rly by block momber)

Two hundred and eighty-eight righthanded males were trained in either an

open skill or closed skill situation in order to determine whether the amount

and variability of practice enhanced transfer to nonpracticed tasks of a similar nature. Subjects in the open skill situation visually tracked a moving light sequence and attempted to complete a ballistic arm movement coincident

with the termination of light movement. Closed skill subjects did not receive

the light sequence but focussed their attention on the production of a.specific

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20. ABSTRACT (continued)

movement time on each trial. Subjects in both situations received either 45 or

180 trials during the training phase. Open skill subjects practiced with a

stimulus velocity-movement distance combination which remained constant or was

varied during training. Closed skill subjects practiced movement time-movement

distance combinations which remained the same or were varied from trial to

trial during training. Following the training phase open skill subjects performed 20 trials with a stimulus velocity-movement distance they had not experienced before while closed skill subjects attempted to produce a new movement time-movement distance combination.

During the training phase open skill subjects who practiced with a variety

of movement distances exhibited higher absolute timing error than those who

practiced with a constant distance. This effect dissipated quickly however

and transfer performance did not appear to be influenced differentially by

constant or varied training conditions. For closed skill subjects, variations

in movement time, and to a lesser extent movement distance resulted in higher

absolute error during training. Moreover, the transfer performance of subjects who trained with a variety of movement times and/or movement distances

was less accurate and less consistent than that of subjects receiving training

with a constant movement time and/or distance. It was suggested that if

closed skill transfer will ultimately be to a single novel version of a

particular task (e.g., repeatedly throwing a grenade at a new target) training

should primarily involve the constant repetition of a single response (particularly with respect to a constant movement time). On the other hand open

skill transfershould not be influenced as much by different levels of

variability during training.

0I

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Technical Report 596

VARIABILITY OF PRACTICE AND THE

TRANSFER OF TRAINING OF MOTOR SKILLS

Craig A. Wrisberg and Timothy P. Winter

University of Tennessee, Knoxville

Contract monitored by Joseph D. Hagman

Approved as technically adequate

and submitted for publication by Robert M. Sasmor, Director

BASIC RESEARCH

U.S. ARMY RESEARCH INSTITUTE FOR THE BEHAVIORAL AND SOCIAL SCIENCES

5001 Eisenhower Avenue, Alexandria, Virgnia 22333

Office, Deputy Chief of Staff for Per sonet

Department of the Army

November 1983

Army Project Number Basic Research

20161 102374F

Appovd for wpei rele. ~d~tUon wamhed.
ARI Research Reports and Technical Reports are intended for sponsors of

R&D tasks and for other research and military agencies. Any findings ready

for implementation at the time of publication are presented in the last part

of the Brief. Upon completion of a major phase of the task, formal recommendations for official action normally are conveyed to appropriate military

agencies by briefing or Disposition Form.

iv
FOREWORD

The Training and Simulation Technical Area of the U.S. Army Research

Institute for the Behavioral and Social Sciences (ARI) maintains a program of

research in support of the systems approach to training. A major focus of

this program is the development of fundamental data and technology in the areas

of skill acquisition, retention and transfer necessary for fielding training

systems that improve individual job performance.

Typically, soldiers are trained in service schools on only a portion of

those tasks required for effective job performance. The remaining tasks are

trained on the job once soldiers arrive in their operational units. Because

unit training resources are limited, a primary goal of school training is to

promote effective positive transfer of school-taught tasks to those additional

tasks required on the job. Such transfer would reduce unit training demands

and promote better on-the-job performance and associated combat readiness.

This basic research report examines the effects of amount and variability

of practice on the transfer of training of motor skills. The findings indicate

that transfer improves with increased initial task training but that the effects

of variety are task specific,\ These and other previous findings from the

Training and Simulation Techbi'al Area are being combined to form the technology

base for improving training an training management effectiveness within the

Army.

\ • /

L~L

//

Edgar M. Johnson

Technical Director

V
VARIABILITY OF PRACTICE AND THE TRANSFER OF TRAINING OF MOTOR SKILLS

BRIEF

Requirement:

To determine whether the amount and variability of movement practice

during motor skills training enhances transfer of training to nonpracticed

tasks of a similar nature; to examine the effects of amount and variability

of practice for both "open" and "closed" motor skills (open skills require

responses to changing environmental conditions while closed skills are performed in a relatively stable environment); to suggest potential application

of the findings in the training of military personnel in order to promote

more effective transfer of motor skills essential for combat readiness.

Procedure:

Two hundred and eighty-eight righthanded males were trained in either

an open skill or closed skill situation. Both situations involved a ballistic

horizontal arm sweep from a start button to a hinged target. Subjects in the

open skill condition visually tracked a moving light sequence and attempted

to complete their response coincident with the termination of light movement. Closed skill subjects did not receive the light sequence but attempted

to produce a specified movement time on each trial. During training subjects

were given either 45 or 180 trials of practice. Variability of practice was

manipulated in the closed skill condition by requiring subjects to perform

a movement distance-movement time combination which either varied or re-

"mained constant from trial to trial. In the open skill situation movement

distance and stimulus velocity were varied or remained constant during training. Knowledge of results in terms of timing error (in milliseconds) were

administered after each trial. Following training closed skill subjects attempted to produce a movement distance-movement time combination which they

had not previously performed. Similarly open skill subjects were given a

new stimulus velocity and movement distance. No knowledge of results were

given during the transfer phase.

Findings:

For the closed skill situation, variations during training in movement

time and, to a lesser extent, movement distance resulted in higher absolute

timing error during the training phase and higher absolute error and variable

error in the production of a novel movement distance-movement time combination

during the transfer phase. In the open skill situation, variations in movement distance elicited initial elevations in absolute timing error during

training but this effect dissipated after about 30 trials. Moreover, manipulations of the variability of movement distance and stimulus velocity during

the training phase appeared to exert little influence on coincident timing in

vii nO-A-M

-SUP - a "-- .-
a novel stimulus velocity-movement distance situation. Subjects who

were trained under fixed movement distance or stimulus velocity conditions significantly reduced their variable error over transfer blocks

while variable trained subjects did not. Subjects who received 180 trials

during the training phase generally performed better during the transfer

phase than subjects who received 45 training trials.

Utilization of Findings:

Decisions regarding the quality and quantity of training experiences

would appear to be more crucial for the learning of closed motor skills

(e.g., throwing a hand grenade at a fixed target) than open skills (e.g.,

accurate estimation of the moment of initiation of an anti-tank response).

If transfer is to a single novel version of a particular closed skill

(e.g., repeatedly throwing a grenade at a new target) it appears that the

trainee would benefit more from constant repetition of a single response

(particularly with respect to a constant movement time) during training.

viii
VARIABILITY OF PRACTICE AND THE TRANSFER OF TRAINING OF MOTOR SKILLS

CONTENTS

PAGE

INTRODUCTION. .. ... ..... ...... ..... .........

METHOD .. .. ..... ..... ...... ..... ..... .. 6

Subjects .. .... ..... ...... ..... ..... .. 6

Apparatus. .. ... ...... ..... ..... ........6

Procedure. .. ... ..... ...... ..... ........7

RESULTS .. .... ..... ..... ...... ..... .... 14

Measures. .. ..... ...... ..... ...... .... 14

Training. .. ... ...... ..... ..... ...... 14

Transfer. .. ... ..... ...... ..... .......14

Closed Skill Training. .. ... ...... ..... .......15

Closed Skill Transfer .. .. ..... ..... ...... ... 15

Absolute Error .. .. ..... ..... ...... ..... 15

Constant Error .. .. .... ...... ..... .......18

Variable Error .. .. ..... ..... ...... ..... 18

Open Skill Training .. .. ..... ..... ...... .... 18

Open Skill Transfer .. .. ..... ..... ...... .... 22

Absolute Error .. .. ..... ..... ...... ..... 22

Constant Error .. .. ..... ..... ...... ..... 25

Variable Error .. .. ..... ..... ...... ..... 27

DISCUSSION .. .. ..... ..... ...... ..... ..... 27

REFERENCES .. .. ..... ..... ...... ..... ..... 36

ix
LIST OF TABLES

PAGE

Table 1. Experimental Design ...... ................... 8

Table 2. Means and Standard Deviations (in

parentheses) for Constant Error During

Transfer Blocks for .the Training Trials x

Movement Distance x Blocks Interaction

(Open Skill Situation) .... ................. .25

LIST OF FIGURES

Figure 1. Subject Standing at Apparatus

in "Ready" Position (Closed

Skill Situation) ....... .................... 9

Figure 2. Subject Contacting Target at

Completion of Timing Movement

(Closed Skill Situation) ...... ................ 10

Figure 3. Subject Standing at Apparatus in

"Ready" Position (Open Skill

Situation) ...... ....................... .12

Figure 4. Subject Contacting Target at

Completion of Coincident

Timing Movement (Open Skill

Situation) ...... ....................... .13

Figure 5. Mean Absolute Error During the

Training Phase for the Movement

Distance x Movement Time x Blocks

Interaction for Closed Skill Subjects

Receiving 45 Trials (9 Blocks) .... ............. 16

Figure 6. Mean Absolute Error During the

Training Phase for the Movement

Distance x Movement Time x Blocks

Interaction for Closed Skill Subjects

Receiving 180 Trials (36 Blocks) .... ............ 17

Figure 7. Mean Absolute Error for the Closed

Skill Transfer Phase as a Function

of Number of Training Trials and

Movement Time Condition During

Training ....... ....................... 19

:ix
Figure 8. Mean Variable Error for the

Closed Skill Transfer Phase as a

Function of Number of Training Trials,

Movement Time Condition During Training,

and Movement Distance Condition

During Training ....... .................... 20

Figure 9. Mean Variable Error for the Four

Blocks of Trials During the

Closed Skill Transfer Phase .... .............. 21

Figure 10. Mean Absolute Error During the

Training Phase for the Movement

Distance x Blocks Interaction for

Open Skills Subjects Receiving

45 Trials (9 Blocks) ..... .................. 23

Figure 11. Mean Absolute Error During the

Training Phase for the Movement

Distance x Blocks Interaction for

Open Skill Subjects Receiving

180 Trials (36 Blocks) ..... ................. 24

Figure 12. Mean Constant Error During Open

Skill Transfer for the Interaction

Between Number of Training Trials

and Stimulus Velocity Condition

During Training ....... .................... 26

Figure 13. Mean Variable Error on the Four

Open Skill Transfer Blocks as a

Function of Number of Trials

Received During Training .... ................ 28

Figure 14. Mean Variable Error on the Four

Open Skill Transfer Blocks as a

Function of Movement Distance

Condition During Training ..... ............... 29

Figure 15. Mean Variable Error on the

Four Open Skill Transfer Blocks

as a Function of Stimulus Velocity

Condition During Training .. ... .............. .30

xi

000
Variability of Practice and the Transfer

of Training of Motor Skills

Craig A. Wrisberg

Timothy P. Winter

Department of Physical Education

University of Tennessee - Knoxville

Two fundamental issues in the learninq of motor skills deal with the

quality and quantity of practice sessions. In order to maximize the efficiency and minimize the cost of training, decisions must be made regarding

the optimal amount and type of practice which will best facilitate learning.

One approach to this issue has recently been proposed by Schmidt (1975) who

has suggested that the skill acquisition process be viewed as an attempt by

the performer to develop general rules of movement which are then used to

govern the production of future responses. At the heart of this veiwpoint is

the notion that a variety of perceptual-motor experiences during training will

promote rule formation to a greater extent than repetition of a single movement. If Schmidt's proposition is correct then the practical implications are

clear: traditional training strategies which emphasize the mere repetition of

responses may need to be amended to include greater variation of perceptual

and/or motor experiences.

Schmidt's (1975) schema theory is rooted in the notion of generalized

motor programs. For example, the motor action involved in throwing might be

postulated to require a generalized program which could be activated to throw

an object faster or slower, higher or lower, and overhand or sidearm. In

addition, objects of different shapes, sizes, and weights might also be accommodated by this program. The idea of the generalized program has a good

deal more theoretical and practical appeal than the notion that a variety of

1
related movements (e.g., throwing a yrenade and throwing a knife) require 1nseparate motor programs for execution (Henry & Rogers, 1960).

According to Schmidt (1975) the four sources of information which subjects

use to construct the generalized program are those concerning a) the preresponse

state of the muscular system and the environment (i.e., initial conditions),

b) the motor plan for generating the movement (i.e., response specifications),

c) feedback stimuli resulting from the actual movement (i.e., sensory consequences), and d) the success of the response in achieving the originallyintended outcome (i.e., degree of goal achievement). The chief aim of practice

on a given task is to provide the performer an opportinity to repeatedly

generate and/or experience the above four sources cf information. After a

number of trials, the subject presumably begins to abstract a relationship

between the various types of information. This abstracted relationship becomes what Schmidt (1975) terms the generalized program or "schema" for the

particular movement class (e.g., throwing). According to Schmidt, a generalized

throwing.program should allow the performer to adapt to each throwing situation

by manipulating the parameters of the program (e.g., amount of force, direction

of throw, selection of appropriate muscle groups) to suit the particular circumstances.

An important prediction of Schmidt's theory is that schema strength is a

function of the amount and variability of perceptual-motor training experiences.

To test this notion studies have typically employed an experimental paradigm

involving a variable practice group which is given several versions of the

task during training and a constant practice group which receives only one

version. At the end of training, the groups are transferred to an instance of

tha task which has not been previously experienced by either group. Such a

h 2
paradigm is not new, having been used for some time by experimental psychologists to study the development of cognitive-conceptual relationships

using tasks such as paired associate learning (Duncan, 1958), geometrical

figure discrimination (Morrisett & Hovland, 1959), and serial learning of

noun lists (Baker, Santa, & Gentry, 1977) and of letters (Ellis, Parente,

Grah, & Spiering, 1975).

Direct tests of Schmidt's (1975) schema theory for discrete motor skills

using the transfer paradigm have produced mixed results. While there has been

consistent support for the variability of practice hypothesis from experiments

with children (Beatty, 1977; Carson & Wiegand, 1979; Kelso & Noman, 1978;

Kerr & Booth, 1977, 1978; Moxley, 1979; Pigott, 1979) the results from studies

with adult subjects have been more equivocal. The majority of the latter investigations have employed rapid (i.e., movement times less than I sec) timing

tasks involving short (i.e., movement distances less than 75 cm) subject-paced

arm movements with variations in either movement time or movement distance.

In the only study using a fixed movement distance, Newell and Shapiro

(1976) trained subjects to make a 10.16 cm movement in a time of either 70 msec

or 130 msec. Constant practice subjects performed 60 trials with knowledge of

results at either the 70 or the 130 msec movement time while varied practice

subjects received the first half of their trials with either the 70 msec or

130 msec movement time and the second half at the other time (the order of

presentation of movement times was counterbalanced). Half of the subjects

in each condition then attempted to perform 20 trials of the task at a movement time of 100 msec while the other half attempted to produce a movement time

of 180 msec. No knowledge of results were given during the transfer trials.

Mixed support was generated for the schema notion when the varied practice

3
subjects who received training trials with the 70 msec movement time followed

by the 130 msec movement time transferred to the 180 msec movement time with

significantly less error than constant practice subjects. Therefore it was

suggested that the order of variable practice might facilitate transfer to a

second task when the movement time for that task was outside the range of

movement times given during training.

In studies utilizing a fixed movement time and varied movement distance

there has again been partial support for the schema notion. McCracken and

Stelmach (1977) trained subjects to produce a movement ranging in length from

15-65 cm in a time of 200 msec. During training vdriable practice subjects

received an equal number of trials (K = 75) with each distance while constant

practice subjects received 300 trials on only one of the movement distances.

Control subjects received 75 trials of practice with one of the distances. In

both the constant practice and the control conditions an equal number of subjects were assigned to each movement distance. When transferred to a 50 cm

distance for 30 trials without knowledge of results, the variable practice

condition exhibited significantly lower absolute error than the other groups.

In a similar experiment conducted by Zelaznik (1977) variable practice subjects attempted to move distances of 15, 25, and 33 cm (24 trials/distance)

in a time of 200 msec while constant practice subjects received either 24 or

72 trials with the 33 cm distance. Accuracy of transfer performance at a

distance of 43 cm was not found to be significantly different for the three

groups. An important methodological difference characterizing the Zelaznik

(1977) study was that all constant practice subjects were trained at the

distance closest in length to the transfer distance. Thus, had variable

practice subjects demonstrated superior transfer more powerful support for tne

4

'
schema notion would have been generated.

Taken together, the results of these studies performed in a relatively

stable environment and referred to as "closed skills" (Poulton, 1957) provide

only modest support for the variability of practice hypothesis. In the only

published experiment investigating timing performance in an "open skill" setting

(i.e., with environmental uncertainty added) initial support for the schema

notion was produced. Wrisberg and Ragsdale (1979) presented subjects with a

moving visual stimulus (i.e., lights illuminating in a pattern of apparent

motion) and instructed them to press a button at the same moment that they

perceived the last lamp in the sequence was illuminating. Prior to transfer

trials with a stimulus velocity of 402 cm/sec subjects received 40 trials in

which they either a) watched, or b) responded to stimuli which a) varied in

speed from trial to trial (velocities ranged from 224 cm/sec to 581 cm/sec)

or b) were the same on each trial. During transfer trials the high variability

group which overtly responded to the visual sequences during training had significantly lower absolute error than the other conditions. It was suggested

however that further study be done using longer limb movements in order to

determine the relative contributions of variations in stimulus (e.g., velocity)

and response (e.g., movement distance) parameters to the development of a

generalized program for open skills.

The present study represented an initial attempt to identify the relative

contribution of spatial and temporal components in the development of generalized

programs for open and closed timing tasks. During training the amount and

variability of practice were independently manipulated. Following the training

phase subjects were transferred to a novel version of their respective tasks

which they performed without knowledge of results.

5
Method

Subjects. A total of 288 male righthanded subjects participated in the

experiment. All of the participants were students at the University of Tennessee,

ranging in age from 18 to 30 years. None of the subjects was familiar with the

test apparatus and all were paid for their participation.

Apparatus. Five microswitches and a hinged and foam-padded plywood target

(11 x 13 cm) were attached to a platform which was mounted on top of a large

table. The 1.5 cm diameter microswitches were separated (center to center) by

a distance of 15 cm and mounted along a line parallel to and 18 cm from the

edge of the table. The distance from the target to the first microswitch was

43 cm and to the second, third, fourth, and fifth microswitches 58, 73, 88 and

103 cm, respectively. A Reaction-Movement Timer (Lafayette Instruments #62017)

was interfaced with the response system. When the target was in the vertical

position it depressed a set of contact points. In the closed skill situation

time began to accumulate on the Reaction-Movement Timer when the subject released one of the response microswitches and stopped when the target was

knocked over, opening the contacts.

A Bassin Anticipation Timer (Lafayette Instruments #50-575) was interfaced with the response platform for use in the open skill situation. This

system included a solid state control unit and a runway which was 285 cm long x

9 cm high x 7 cm wide. Mounted on top and running the length of the runway

were 64 small (.5 cm diameter) lamps, separated center to center by a distance

of 4.45 cm. The runway was mounted in a line extending out from the target and

parallel to the response microswitches. In the open skill situation target

contact resulted in a digital display which indicated the algebraic difference

(i.e., early vs. late target contact) in msec between the moment of target con6
tact and the moment of illumination of the last lamp (i.e., the one nearest

the target) in the sequence.

Procedure. The experiment was composed of two phases, a training phase

and a transfer phase (Table 1). Subjects assigned to the closed skill situation were instructed to produce a particular movement time on each training

trial. The subject stood facing the response platform with the target situated

to his left. Prior to each trial the subject was told a movement time which

he was to attempt to produce. He was then instructed to depress one of the

response microswitches with the index finger of his right hand (Figure 1). When

he was ready the subject made a ballistic right to left arm movement from the

microswitch to the hinged target (Figure 2), attemipting to traverse the distance

in the instructed movement time. Following each trial the experimenter verbally

reported the actual movement time produced (in msec) and indicated whether it

was faster or slower than the instructed time. The spatial and temporal factors

manipulated during training in the closed skill situation were movement distance and movement time, respectively. As indicated in Table 1, closed skill

subjects received either 45 or 180 training trials in which movement distance

and/or movement time was either constant or varied from trial to trial. An

equal number of subjects (n = 18) were randomly assigned to each of the eight

possible combinations of training trials (2) x movement distance (2) x movement

time (2). Following training all closed skill subjects performed 20 transfer

trials without knowledge of results in which they attempted to move a distance

of 43 cm in a time of 300 msec.

Subjects assigned to the open skill situation were instructed to produce

a ballistic movement which terminated with target contact at the same moment

that the last lamp in a sequence of runway lights was illuminating. As in the

7
Table I

Experimental Design

Training Phase Transfer Phase

Type Number Number

of of Movement Movement of Movement Movement

Task Trials Distance Time* Trials Distance Time*

45

or Fixed (58 cm) Fixed (400 msec) 20 43 cm 300 msec

180

45 Varied (58, 73, Fixed (400 msec) 20 43 cm 300 msec

or and 103 cm) 180

Closed

45 Fixed (58 cm) Varied (400, 600, 20 43 cm 300 msec

or and 700 msec)

180

45 or Varied (58, 73, Varied (400, 600, 20 43 cm 300 msec 180 and 103 cm) and 700 msec)

45

or Fixed (58 cm) Fixed (224 cm/sec) 20 43 cm 179 cm/sec

180

45 Varied (58, 73, Fixed (224 cm/sec) 20 43 cm 179 cm/sec

180or and 103 cm)

Open

45 or Fixed (58 cm) Varied (224, 268, 20 43 cm 179 cm/sec 180 and 358 cm/sec)

45 Varied (58, 73, Varied (224, 268, 20 43 cm 179 cm/sec 180 and 103 cm) and 358 cm/sec)

* "Stimulus Velocity" for the open skill situation

8
Figure 1.

Subject Standing at Apparatus in

... ~~. 

"Ready Poito " (Coe Skl itain

9.
6 •-

Figure 2.

Subject Contacting Target at Completion of

Timing Movement (Closed Skill Situation)

10

o
closed skill situation the subject stood in front of the response platform

with the target to his left and the runway extending horizontally out from

the target. Prior to each trial the subject was instructed to depress one

of the microswitches with the index finger of his right hand. He was then

told to turn his head to the left and to focus his attention on the furthest

end of the runway (Figure 3). This instruction was designed to orient the

subject for subsequent visual tracking of the sequence of apparent motion.

When this occurred the subject watched the moving stimulus and then attempted

to produce a ballistic right-left arm response, originating from the microswitch and terminating at the target at the same moinc. that the last lamp

on the runway nearest the target was illuminatinq (Figure 4). Following each

training trial the experimenter verbally reported the difference (in msec) between the moment of illumination of the last lamp and the oment of target

contact. The subject was also told whether target contact was made "too early"

(i.e., before the last lamp illuminated) or "too late" (i.e., after cessation of

the illumination period for the last lamp). The spatial and temporal factors

manipulated during training in the open skill situation were movement distance

and stimulus velocity, respectively. As indicated in Table I open skill subjects received either 45 or 180 training trials in which movement distance and/or

stimulus velocity was either constant or varied from trial to trial. An equal

number of subjects (n = 18) were randomly assigned to each of the eight possible

combinations of training trials (2) x movement distance (2) x stimulus velocity (2).

Following training all open skill subjects performed 20 transfer trials without

knowledge of results in which they moved a distance of 43 cm in an attempt to

time the completion of a visual stimulus moving at a speed of 179 cm/sec.

Closed skill subjects in the varied-varied condition received an equal

11
II

Figure 3.

Subject Standing at Apparatus in

"Ready" Position (Open Skill Situation)

12

7
Figure 4.

Subject Contacting Target at Completion of

Coincident Timing Movement (Open Skill Situation)

13
number of trials with each or the iine possible combinations of movement distance and movement time. Open skill subjects assigned to the varied-varied

condition performed an equal number of trials with each of the nine possible

combinations of movement distance and stimulus velocity. Groups which practiced

with one fixed and one varied factor received an equal number of trials with

each of the three levels of the varied factor. Subjects who received 180

training trials were given a two-minute rest between eacn block of 45 trials

and, for all subjects, a two-minute rest was interpolated between the training

and transfer phases of the experiment. An intertrial interval of 10 sec was

maintained throughout training and transfer perfortr..:.

Results

Measures

Training. The dependent measure of interest was mean absolute error

(AE). For the closed skill situation AE represented the absolute difference

(in msec) between actual and desired movement time averaged for each subject

over blocks of five trials. For open skill subjects AE was calculated as the

absolute difference (in msec) between the moment of target contact and the

moment of illumination of the last lamp in the runway sequence. These scores

were also averaged over blocks of five trials for each subject.

Transfer. Three dependent measures were recorded during the transfer phase

of the experiment. In addition to AE (averaged for each block of five trials),

constant error (CE) and variable error (VE) were also derived from the scores

of each subject. The former measure represented the algebraic deviation of a

subject's response from the correct movement time (closed skill) or moment of

coincidence (open skill), averaged over each block of five trials. The VE

measure was obtained by calculating the standard deviation of a subject's CE

14

... . .-... .. Mm--. . . . .... . . ... m . . .. . . . ... . . . .I
scores around his mean CE. for each block (see Schutz & Roy, 1973, for a more

detailed discussion of these measures).

Closed Skill Training

The mean AE scores for closed skill subjects were assessed by a movement

distance (2) x movement time (2) x blocks ANOVA with repeated measures on the

last factor. Separate ANOVAs were run for subjects receiving 45 training

trials (9 blocks) and for those receiving 180 training trials (36 blcks).

Both ANOVAs revealed a highly significant three-way interaction of movement

distance x movement time x blocks, F(8,544) = 5.94, r. .001 (9 blocks), and

F(35,2380) = 3.30, p<.0 0 1 (36 blocks). These interactions are presented in

Figures 5 and 6. In each case it is clear that while decreases in timing

error were taking place for all groups over blocks, those subjects who received a variety of movement times during training produced higher errors than

those who trained with a constant movement time. Only when movement time was

varied did further variations in movement distance appear to result in greater

timing error; however, this effect seemed to disappear after about 24 blocks

(or 120 trials) of practice (Figure 6).

Closed Skill Transfer

The mean AE, CE, and VE scores for closed skill subjects were assessed

by means of separate training trials (2) x movement distance (2) x movement

time (2) x blocks (4) ANOVAs with repeated measures on the last factor. A

Newman-Keuls post hoc analysis was performed to locate the source of significant

differences involving three or more means.

Absolute error. The only significant effects obtained for AE were the

main effects of training trials, F(1,136) = 10.21, p<.01, and of movement time,

F(1,136) = 6.50, p<.01. As can be seen in Figure 7 AE during the production

15
0

w

04

(02 I

1 2 3 4 5

TING BLOC

w 80 D FigureV-5.

Mean Aslt Ero DuingteTann hs o h

Movement ~ ~ ~ DitncV-MDmn Tm Bok Itrcofr

Close 60 il SujcsRciig4 ras( lcs

o I'I16
w

(0 140-

1t20 -

0.

100

w

0 80 t

0 t te MTV M

Z 20 MTC-MDC

36 9 12 1518212427'3033 36

TRAINING BLOCK

Figure 6.

Mean Absolute Error During the Training Phase for the

Movement Distance x Movement Time x Blocks Interaction for

Closed Skill Subjects Receiving 180 Trials (36 Blocks)

17

" '00-
C140-

~120 -

0.

C 100

MTV-MDV

0 t" MTV-MDC

m40

z 20 MTC-MDC

36 9 121518 21242 73 03336

TRAINING BLOCK

Figure 6.

Mean Absolute Error During the Training Phase for the

Movement Distance x Movement Time x Blocks Interaction for

Closed Skill Subjects Receiving 180 Trials (36 Blocks)

17
of a novel movement distance-movement time combination was lower for subjects

who received a greater number of training experiences and for those who attempted to produce a constant movement time during training.

Constant error. No significant main or interaction effects were obtained for CE. Thus, it appeared that neither the amount nor the type of

training produced any bias (i.e., responses that on the average were too fast

or too slow) in the execution of the novel transfer movement.

Variable error. For VE, significant main effects were obtained for

training trials, F(1,136) = 4.54, p <.05, movement distance, F(1,136) 6.66,

R<.01, movement time, F(1,136) = 8.95, p< .01, and blocks, F(1,136) 3.64,

< .01. As can be seen in Figure 8, average within-subject variability in

the production of the novel movement distance-movement time combination was

lower for subjects who a) received more training trials, b) trained with a

constant movement distance, and c) trained with a constant movement time.

Figure 9 presents the means for the significant blocks effect. Inspection of

this figure indicates that the largest reduction in VE occurred from the first

block of transfer trials to the second block. Newman-Keuls procedures revealed

that VE on Block 1 was significantly different from that on Block 2 (P <.01)

and Block 4 (p <.05). Thus, it appeared that all subjects settled into a preferred movment pattern fairly early in the transfer phase and, in the absence

of knowledge of results, tended to repeat that movement with the same level of

consistency over the remaining transfer trials. No other significant main or

interaction effects were obtained for VE.

Open Skill Training

The mean AE scores for open skill subjects were assessed by a movement

distance (2) x stimulus velocity (2) x blocks ANOVA with repeated measures on

the last factor. Separate ANOVAs were performed on the data of subjects re18
~70O

M 65--

0

M 60, uJ A

w55

I A

0 I

S I

45 180 CON VAR

TRAINING MOVEMENT

TRIALS TIME

Figure 7.

Mean Absolute Error for the Closed Skill Transfer Phase

as a Function of Number of Training Trials and

Movement Time Condition During Training

19
w 35

0

< 25

,< 20-,

w,

45 180 CON VAR CON VAR

TRAINING MOVEMENT MOVEMENT

TRIALS TIME DISTANCE

Figure 8.

Mean Variable Error for the Closed Skill Transfer Phase

as a Function of Number of Training Trials, Movement Time

Condition During Trainlig, and Movement Distance-Condition During Training

20

t 5 

S
C,45

rr 4 0

o

~35-

w

w3 0 -

25

4 2o

z

w T

1 2 3 4

TRANSFER BLOCK

Figure 9.

Mean Variable Error for the Four Blocks of

Trials During the Closed Skill Transfer Phase

21
ceiving 45 training trials (9 blocks) and those of subjects receiving 180

training trials (36 blocks). For the former analysis, significant main

effects were found for movement distance, F(1,68) = 3.85, p<.05, and for

blocks, F(8,544) = 7.98, p<.01. In Figure 10 the means are presented for

the groups receiving fixed and varied movement distances during 9 blocks of

training trials. It appeared that while both groups improved the absolute

accuracy of their coincidence responses over blocks, subjects who trained

at various movement distances, experienced greater difficulty in timing the

completion of the moving light stimulus. The ANOVA conducted on the scores

of subjects receiving 180 trials during the trainin,i pijse seemed to indicate

that the impact of variations in movement distance was becomming less noticeable

with extended practice. Figure 11 graphically illustrates that by about Block 7,

AE scores for fixed and for varied movement distance groups were not appreciably

different. In addition to a significant main effect of blocks, F(35,2380)

12.63, p<.0 0 1 , there was a significant interaction of movement distance and

blocks, F(35,2380) = 1.72, p<.0 1 , which supported the notion that the influence

of variations in movement distance was present only during early training trials.

No other significant main or interaction effects were found for AE during the

training phase of the study.

Open Skill Transfer

The mean AE, CE, and VE scores for open skill subjects were assessed by

means of separate training trials (2) x movement distance (2) x stimulus

velocity (2) x blocks (4) ANOVAs with repeated measures on the last factor.

A Newman-Keuls post hoc analysis was performed to locate the source of significant differences involving three or more means.

Absolute error. The analysis of AE revealed no significant main or inter22
r0

----- .o....

w

0

0

M: 60 '.

UJ 50 MDV .

0MDC

-J40

0

CD,

o 30 4" 

z t

123456789

TRAINING BLOCK

Figure 10.

Mean Absolute Error During the Training Phase for the Movement Distance x Blocks Interaction for

Open Skills Subjects Receiving 45 Trials (9 Blocks)

23
80

MDV

70

M 60

w

50

S40

0

-J 0 MDC AL'.A

S30

z

6 12151822427303336

TRAINING BLOCK

Figure 11.

Mean Absolute Error During the Training Phase for the

Movement Distance x Blocks Interaction for Open Skill Subjects Receiving 180 Trials (36 Blocks)

24
effects. Thus, it appeared that the absolute accuracy of a coincidence

response involving a movement distance and stimulus velocity which had not

previously been experienced was not influenced by either the amount or type

of previous training experiences.

Constant error. For CE a significant interaction between training trials

and stimulus velocity was obtained, F(1,136) = 5.30, p<.05. This interaction,

presented in Figure 12, seemed to be caused primarily by differences in the CE

performance of the groups receiving 45 training trials. Newman-Keuls procedures

revealed that the CE of subjects receiving a constant stimulus velocity during

45 trials of training was significantly (p < .05) dif.rent from that of subjects who received varied stimulus velocities during their 45 training trials.

The response bias of the former group was characterized by slightly early anticipations while that of the latter revealed an average tendency by subjects

to strike the target after the illumination of the last lamp in the sequence.

No difference was obtained between the CE of constant and varied stimulus

velocity subjects receiving 180 training trials.

The only other significant effect for CE was a training trials x movement

distance x blocks interaction, F(3,408) = 3.61, P< .01. The means and standard

deviations for this interaction are presented in Table 2. While Newman-Keuls

Table 2

Means and Standard Deviations (in parentheses) for

Constant Error During Transfer Blocks for the

Training Trials x Movement Distance x Blocks Interaction (Open Skill Situation)

Training Movement Number of

Distance Training Trials 1 2 3 4

Constant 45 16(43) -1(42) 2(41) 3(42)

180 1(36) 11(37) 5(31) -2(37)

Varied 45 0(50) 6(50) 2(36) 8(31)

180 0(29) -4(30) -3(30) -5(28)

25

i!i
~15

Cr 10- 45

M 5-

z 0-

180

co,

z

0-10.

Z - 1 5 -

CONSTANT VARIED

STIMULUS VELOCITY

Figure 12.

Mean Constant Error During Open Skill Transfer for the

Interaction Between Number of Training Trials and

Stimulus Velocity Condition During Training

26
analysis revealed no significant (p<.05) pairwise differences, it appeared

that subjects who received a constant movement distance during 45 trials of

training had more difficulty adjusting initially (i.e., on Block 1) to the

transfer movement distance-stimulus velocity combination than did the other

groups.

Variable error. There were three significant interactions, all involving

the blocks factor, obtained for VE. These interactions, presented in Figures 13,

14, and 15 were training trials x blocks, F(3,408) = 3.32, p <.05, movement

distance x blocks, F(3,408) = 2.87, p <.05, and stimulus velocity x blocks,

F(3,408) = 3.51, p <.05, respectively. While no significant (p< .05) pairwise

differences were obtained from the Newman-Keuls analysis for the training

trials x blocks interaction (Figure 13), it appeared that the within-subject

variability of coincidence responses for subjects receiving 180 training trials

was slightly less on Blocks 2 and 3 of the transfer phase than that of subjects

who received 45 training trials. With respect to the movement distance x blocks

analysis, subjects receiving a constant movement distance during training significantly reduced their within-subject variability over blocks on the transfer

task while subjects who received varied distances during training did not

(Figure 14). Specifically, the VE of subjects in the fixed distance training

condition, was significantly (p<.05) less on Blocks 3 and 4 than it was on

Block 1. In a similar fashion, VE of subjects receiving a single stimulus

velocity during training trials (Figure 15) was significantly (P<.05) reduced

over transfer performance (i.e., VE on Block 1 was higher than that on Block 3)

while that of subjects who trained with a variety of stimulus velocities was not.

Discussion

According to Schmidt's (1975) schema theory of discrete motor learning,

27
50--5

44

0

M 40--e

w 35 180

-J

<30

,25

zWI

1 2 3 4

TRANSFER BLOCK

Figure 13.

Mean Variable Error on the Four Open Skill Transfer Blocks

as a Function of Number of Trials Received During Training

28
5O

CrM 45 D . . . .. . .

m40

u 3 5

S30

< 25

z

w

1 2 3 4

TRANSFER BLOCK

Figure 14.

Mean Variable Error on the Four Open Skill Transfer Blocks

as a Function of Movement Distance Condition During Training

29
50

C 4 5 - v

0

w

w 3 5 -Sv

-j

~30-

< 25

12 3 4

TRANSFER BLOCK

Figure 15.

Mean Variable Error on the Four Open Skill Transfer Blocks

as a Function of Stimulus Velocity Condition During Training

30
subjects over practice develop a generalized program for a particular class

of responses (e.g., throwing). Schmidt specifically predicts that the strength

of the program will be a function of the amount and variability of experiences

the subject encounters during training. The present study attempted to test

this prediction by manipulating the amount and variability of practice given

on two different types of discrete timing tasks.

The first involved a closed skill (Poulton, 1957) in which subjects

practiced making a ballistic arm movement from a start switch to a padded

target. During training subjects received either 45 or 180 trials in which

movement distance and/or movement time was fixed and/or varied from trial to

trial. During this phase subjects were more accurate when movement time was

held constant than when it was varied from trial to trial. Variations in

movement distance had little influence on timing accuracy unless they were

paired with variations in movement time. However, any error due to variations

in movement distance disappeared after approximately 120 training trials. These

results seem to coincide with the observation of Lordahl and Archer (1958) that

variations in the temporal dimensions of a timing task cause greater disruptions

in accuracy than do variations in spatial parameters. Moreover, the present

finding of a transitory influence on performance due to variations in movement

distance is consistent with the published results of Fleishman and Rich (1963)

which demonstrated that spatial factors (e.g., movement distance) are more important primarily during the early phases of perceptual-motor performance.

In order to assess the strength of the generalized motor program developed

during training subjects were transferred to a movement distance-movement time

combination which they had not previously attempted. Schmidt's (1975) prediction

of superior transfer performance by closed skill subjects who received a greater

31

4.-
number of training trials was supported by the results of the ANOVAs performed on the AE and VE scores. Both the absolute accuracy and the withinsubject consistency of subjects who received 180 training trials were superior

to that of subjects who practiced for 45 trials. However, the prediction that

the quality of transfer performance would be an increasing function of the

variability of training experiences was not supported. In fact, where significant differences were obtained, the means were in the direction opposite

to that predicted by the theory. Specifically, subjects who trained with a

variety of movement times were less accurate (i.e., higher AE) and less consistent (i.e., higher VE) during transfer performance than their counterparts

who trained with a constant movement time. In addition, subjects who performed

with a variety of movement distances during training demonstrated higher withinsubject variability during transfer performance than those who trained with a

constant movement distance. Taken together the results of the transfer analysis

for the closed skill situation suggest that variability in either the temporal

or spatial dimensions of a discrete timing movement may not produce the most

appropriate memorial representation for the production of a novel movement of

the same general class.

That these results conflict with the findings of two earlier studies

(McCracken & Stelmach, 1977; Newell & Shapiro, 1976) may be due to the fact

that transfer in the present study was to a version of the task which required

the production of both a new movement time and a new movement distance. In the

earlier studies either movement time (McCracken & Stelmach, 1977) or movement

distance (Newell & Shapiro, 1976) was the same for both the training and transfer

phases of performance. Thus, it is possible that the transfer predictions of

schema theory (Schmidt, 1975) may only apply in closed skill situations in which

32

I_,
subjects are transferred to a version of the task which has at least one

dimension in common with that experienced during training. Further investigation of this issue is obviously needed.

The second situation explored in the present study involved the acquisition

and transfer of an open skill (Poulton, 1957). In this situation subjects

performed a ballistic arm movement which they attempted to complete (i.e., by

striking a hinged target) at the same moment that a visual light pattern was

completing its sequence. During training subjects received either 45 or 180

trials in which movement distance and/or stimulus velocity was fixed and/or

varied from trial to trial. The results from the training phase indicated

that variations in movement distance resulted in lower absolute accuracy of

anticipations. However, this influence which appeared to vanish early in

training (i.e., after approximately 30 trials of practice), is consistent

with the finding of Fleishman and Rich (1963) that spatial factors are primarily

important during the initial stages of performance on an open timing task.

Following training all subjects received 20 transfer trials with a movement distance-stimulus velocity combination that they had not previously experienced. With respect to absolute accuracy (i.e., AE) of transfer performance

it did not appear that differences in either the amount or variability of training experiences influenced the production of a novel coincidence anticipation

response. Moreover, given sufficient practice (i.e., more than 50 trials)

there was no evidence that response bias (i.e., CE) on the transfer task was

influenced by variations in movement distance or stimulus velocity during

training. With respect to within-subject variability during transfer performance

subjects who trained under fixed movement distance or stimulus velocity conditions adjusted more rapidly (i.e., manifested significant decreases in within33
subject variability over transfer blocks) to the novel movement distancestimulus velocity combination than did subjects trained under varied conditions.

All in all the results from the open skill situation suggest that differences in the amount or variability of training experiences are of little

importance to the performance of a novel movement distance-stimulus velocity

combination. The lack of consistency of this result with that reported by

Wrisberg and Ragsdale (1979) may be due to differences in the amount of training given in the two studies. It may be that a brief amount of varied practice

on an open skill has a temporary benefit for immediate transfer to a new version

of the task (Wrisberg & Ragsdale, 1979). However, extended practice (as in the

present study) might be expected to produce similar levels of transfer to a

novel version of the task regardless of the extent to which training is varied.

From a practical standpoint the results of the present study suggest that

decisions regarding the quality and quantity of training experiences are more

crucial for the learning of closed skills (e.g., throwing a hand grenade at a

fixed target) than open skills (e.g., accurate estimation of the moment of

initiation of an anti-tank response). Of particular importance is the implication that variations in the movement time, or to a lesser extent the

movement distance of a closed timing movement during training may lead to

greater errors in the production of a subsequent movement distance-movement

time combination which has not been previously attempted. Thus, it might be

concluded that transfer to a single novel version of a particular closed skill

(e.g., repeatedly throwing a grenade at a new target) would benefit most from

constant practice (i.e., fixed target, movement distance, and movement time)

during initial training.

A potentially significant line of future inquiry would be to determine

34
which type of practice, varied or constant, would promote transfer to a

variety of novel versions of a closed task (e.g., throwing grenades at a

number of previously unpracticed targets). In light of recent theorizing

which addresses the potential of context effects on performance and learning

(Jenkins, 1977; Tulving & Thompson, 1973) it might be argued that varied

practice in the present study would have been more appropriate if closed

skill transfer were to a context involving the production of a variety of

novel movements. As it was, transfer performance occurred in a constant

context (i.e., fixed movement distance and fixed movement time) while training performance ranged from completely constant (i.e., fixed movement distance-fixed movement time) to completely varied (i.e., varied movement distance-varied movement time). More research is obviously needed to sort out

the role of context effects in the training and transfer of closed skills.

35
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